Punch with integral stripper



July 31, 1951 N. B. GRANBERG PUNCH WITH INTEGRAL STRIPPER Filed Dec. 22,1947 (il m FIG. 3.

Neil B. Grunberg INVENTOR. BY f ATTORNEY.

Patented July 31, 1951 2,562,267' PUNCH WITH INTEGRAL STRIPPER Neil B.bGranberg, Milwaukee, Wis., assigner-to A. 0. Smith Corporation,Milwaukee, Wis., a 'corporation of New York Application December 22,1947, Serial No. 793,281

3 Claims. l

has particular reference to a stripping punch.

with an integral stripper.

The principal object of the invention is to provide a compact punchingltool that will do the same work of more complicated punches.

Another object is to provide a less costly resilient assembly forwithdrawal of the punch after the punching operation is accomplished andwhich will stand up in service.

A further object is to provide a punching tool which is readilyassembled.

These and lother. objects of the invention will appear hereinafter inconnection with the followf ing description of the drawing illustratingan embodiment of the invention.

In the drawing:

Figure l is a longitudinal sectional view of the punching tool of theinvention with the punch in elevation and in retracted position;

Fig. 2 is a view similar to Fig. 1 with the punch in extended position;

Fig. 3 is a detail view of the lower portion of the punch beingretracted from thework and showing the hold down of the work; and

Fig. 4 is a section taken on line 4-4 of Fig. l.

Referring to the drawing, there is shown the punch I the upper end ofwhich is disposed within the punch holder or ram 2 and removably securedthereto by the set screw 3 which is threaded into the ram and extendsinto an aperture provided therefore in punch I. The lower end of thepunch tapers to the punching head size desired.

The metal stripper member 4 surrounds punch I below ram 2 and is carriedby and radially spaced from the punch. Member 4 is preferably in theform of a tube of substantial diameter and which is capable of holding athin sheet metal work piece down evenly on al1 sides of the punch duringstripping of the latter from the work piece.

The resilient member 5, which may be of rubber or similar material, islocated in the space between punch I and tubular stripper 4. Member 5extends downwardly from the upper end of stripper 4 to a line slightlybeyond the middle of the stripper and is cemented or vulcanized to bothtubular stripper 4 and punch I to operate integrally with them as willbe described. The punch has a greater cross-section in the portionembraced by member 5 and tapers to the punching head below member 5 aspreviously described.

The lower end portion of tubular stripper 4 projects slightly beyondpunch I when the punching tool is assembled in order to engage theworkpiece 6 being punched before punch I engages the workpiece duringthe working stroke of ram 2, and'to leave workpiece 6 after the punchhas been'withdrawn by the ram. This manner of assembly of tubularstripper 4 with punch I provides the tube as the hold-down element ofthe tool to hold workpiece B tightly against die I upon retraction ofpunch I when the punching operation is completed.

The upper end of stripper 4 is spaced from 1am 2 in order to provideclearance for movement of ram 2 downwardly to drive punch I downwardlythrough workpiece 6, as illustrated in Fig. 2 of the drawing. f

Figures 1, 2 and 3 illustrate the operation of the punching tool. InFig. 1 the tool is shown at the start of a punching stroke as the lowerend of stripper 4 engages the metal sheet or workpiece 6 to be punchedto hold the same tightly down against the die 'I.

In Fig. 2, punch I has been driven through workpiece 6 into die 1. Inthis position of the punch, resilient member 5 is distorted or-offsetdownwardly, as shown in the drawing, since it is placed under tension bypunch I moving downwardly through stripper tube 4.

When ram 2 is retracted, punch I is raised and resilient member 5, asshown in Fig. 3, tends to hold stripper 4 against' workpiece 6 to clampthe workpiece tightly against die I so that the punch is retractedwithout burring or tearing the metal of the workpiece.

By providing a structure in which the stripper normally extends beyondthe end of the punch it is possible to build up a substantial Workingpressure on the stripper by reason of the distortion of the rubber atthe time punch I engages the workpiece. This construction insures aholding down of the workpiece by the stripper until the punch is clearof the workpiece during withdrawal of the punch.

The mechanism for the operation of ram 2 is not shown as it forms nopart of the invention.

The assembly of the tool may be accomplished in a number of differentways. Under one method of assembly the resilient member 5 is assembledin the space between tubular stripper 4 and punch I and then vulcanizedto both members simultaneously. The rubber or rubber-like materialemployed might also be extruded into place. Member 5 may also beprepared with cement and be cemented to both stripper 4 and punch Isimultaneously. After assembly of the tool, as described, the upper endof the punch is then inserted in ram 2 and set screw 3 is threaded intothe aperture provided therefor.

The punching tool of the invention is a very compact unit and the partsare readily assembled., 'I'he integral feature of the assembly isaccomplished by an inexpensive resilient member secured to the other twoparts of the punch.

Various embodiments of the invention may be employed within the scope ofthe accompanying claims.

I claim:

1. A punching tool for punching an aperture in a workpiece, comprising apunch, a tubular stripper surrounding the same in radially spacedrelationship thereto and having an end portion projecting slightlybeyond the lower end of the punch, and a resilient rubber-like materialdisposed in the radial space between the punch and stripper and bondedto both of said members to hold said stripper against the workpiece forstripping said workpiece from the punch during retraction of the punchtherefrom.

2. A punching tool for punching an aperture in a metal workpiece,comprising a. punch, atubular stripper surrounding the same in radiallyspaced relationship thereto and having an end portion projectingslightly beyond the lower end of the punch, and a. resilient rubber-likematerial disposed in the radial space between the punch and stripper andbonded to both of said members to form an integral unit thereof and holdsaid stripper against the workpiece for stripping said workpiece fromthe punch during retraction of the punch therefrom.

3. A punching tool for punching an aperture in a metal workpiece,comprising a punch having the lower end portion tapered to a punchingshape and the upper end secured within a punch holder for operating thesame, a tubular stripper assembled around said punch in spaced relationthereto and projecting beyond the punch at the lower end and spaced fromthe work holder at the upper end, and a resilient rubber-like materialconfined between the tubular stripper and punch above the tapered lowerend portion of the punch and bonded to each of said members tointegrally join the same together and hold said stripper against theworkpiece for stripping the workpiece from the punch during retractionof the punch therefrom.

NEIL B. GRANBERG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,160,676 Richard May 30, 19392,230,043 Moran Jan. 28, 1941 2,327,113 Krotz Aug. 17, 1943 2,391,553Decker Dec. 25, 1945 OTHER REFERENCES Publication: Stee1; (published atCleveland, Ohio). vol. 113, #11 (September 13, 1943), page 104.

